| Nasopharyngeal carcinoma is the second most common malignancy in southern
China and is high in incidence among some native American populations. Nonkeratinizing
nasopharyngeal carcinomas are uniformly associated with Epstein-Barr virus; patients
usually have increased levels of immunoglobulin A antibody to the viral capsid antigen and
early antigen. Pathology: About 85% are squamous cell carcinomas or its lymphoepithelial variants (Schmincke's or Regaud's tumor), 10% lymphomas, and 5% other histologic types (undifferentiated carcinoma, melanoma, plasmacytoma, angiofibroma of childhood). Presentation: Nasopharyngeal tumors spread directly through the pharyngeal space to the structures in or near the cavernous sinus and the foramina of the middle cranial fossa (including the gasserian ganglion and its branches). Destruction in the parasphenoid bones and nerve compression can result in severe pain and nerve palsy. Cranial nerve VI, which passes around the brain stem and along the cavernous sinus, is usually the first nerve to be affected, resulting in a lateral rectus muscle paresis. Common symptoms and signs: Enlarged neck nodes, headache, epistaxis, nasal obstruction (often unilateral), unilateral decreased hearing secondary to eustachian tube obstruction, sore throat (inferior extension), and pain on neck extension. Retrosphenoidal syndrome usually starts with the sixth cranial nerve and subsequently involves cranial nerves II through VI. Symptoms include unilateral ophthalmoplegia, pain, ptosis, trigeminal neuralgia, and unilateral weakness of muscles of mastication. Syndrome of the retroparotid space results from nodal compression of cranial nerves IX through XII and of sympathetic nerves at the base of the skull. Symptoms include difficulties with swallowing, taste, salivation, and respiration; weakness of the trapezius, sternocleidomastoid muscles, homolateral tongue, and soft palate; and Horner's syndrome. Lymphatic drainage:Because the tumor is relatively anaplastic and the nasopharynx has a rich lymphatic network, these carcinomas may spread to lymph nodes when the primary tumor is small.First involved are the retropharyngeal and lateral pharyngeal nodes, followed by the upper cervical nodes. Involvement of the high, posterior cervical nodes is characteristic. Lymphadenopathy is present in 80% of patients at presentation; 50% is bilateral. Treatment of primary tumors. RT alone (bilateral) is used for both the primary tumor and the regional nodal metastases. Surgery is not feasible because of the inadequacy of the surgical margins at the base of the skull and the frequent involvement of the retropharyngeal and cervical nodes bilaterally. Treatment of regional nodes: RT is the treatment of choice. Neck dissection is reserved for adenopathy that persists or regrows after irradiation in patients with apparently controlled primary tumors. Gross reappearance of the cancer at the primary site can be retreated with additional external-beam RT or the placement of a removable radioactive source in the nasopharynx. Such retreatment is only moderately successful and may often produce long-term side effects. Local tumor control rate exceeds 90% for T1 to T3 primary cancers. Control of cervical adenopathy by RT is equally successful. |
